جستجوی مقالات مرتبط با کلیدواژه "بجنورد" در نشریات گروه "آبخیزداری، بیابان، محیط زیست، مرتع"

Finding the potential of groundwater resources is one of the basic principles in water resources management. The aim of this research is to determine the potential of groundwater using support vector machine learning (SVM) models as well as metaheuristic algorithms (hybrid support vector machine model and the bee metaheuristic optimization algorithm (SVM-BA) and hybrid model of the support vector machine and particle swarm optimization algorithm (SVM-PSO).

The factors of elevation, slope, aspect, topographic humidity index, distance from stream, drainage density, distance from fault, lithology, topographic position index, land roughness index, relative slope position and flow convergence index were selected in Bojnurd region. Information on the location of 359 springs was received from the regional water company. Random division algorithm was used to divide training points (70%) and validation points (30%). Based on the removal sensitivity analysis, the importance and contribution of the input variables in determining the groundwater potential were determined. The accuracy of the models was evaluated in two stages of training and validation based on the receiver operating characteristic (ROC) curve method.

The evaluation of the accuracy of the models based on the evaluation criteria of the area under curve (AUC) showed that the prediction accuracy of the hybrid model of the support vector machine and the particle swarm optimization algorithm (SVM-PSO) is 0.945 more than other models (SVM: 0.918 and SVM-BA: 0.932). Based on the results of the superior model, the high potential class and the very high potential class accounted for 7.75% and 38.66% of the area respectively. Among the factors, relative slope position with 14.5%, distance from the fault with 13.4% and lithology with 12.3% were the most important in predicting groundwater potential.

Based on the results of this research, the support vector machine model has a high performance, and two optimization algorithms, the bee metaheuristic and particle swarm optimization algorithm, strengthen the predictive power of the model. Also machine learning models can identify the relationship between the environmental factors and the water supply of the springs and determine their role by using the available data. The relative slope position factor was identified as the most important variable and the distance from the fault factor was considered as the second most important variable in the present study. The results of the research showed that the faults in the region play an important role in aquifer recharge, storage and flow of groundwater. The lithological factor was also introduced by the model as the third important variable in identifying the state of groundwater potential. In this research, by presenting the groundwater potential map, it is possible to plan and verify land use planning for the Bojnurd watershed.

Rainfall erosivity factor is the first noticeable point in soil erosion issues that plays very important role in detachment of soil particle from the origin bed. Hence, investigation of rainfall erosivity factor trend is necessary in decision-making and planning in order to manage soil and water resources. However, studies on various aspects of erosivity like trend and in interaction with precipitation and SPI index have not been attended well. The present study therefore aimed to investigate the rainfall erosivity factor trend based on the Fournier index in 28 stations throughout North-Khorasan Province during the period of 1987 to 2006 by using the Mann-Kendall test. In addition, the SPI and precipitation trend were comprehensively investigated for better characterization of erosivity trend analysis. Results showed that Noushirvan, Faruj, Ayerqayeh and Gholaman stations had decreasing trend and other study stations (71.85%) had increasing trend in the modified Fournier erosivity index. The SPI and precipitation in the study area indicated that most of the stations (89.28%) excluding Khartot, Noushirvan, Faruj and Ayerqayeh had increasing trend. The maximum and the minimum values of modified Fournier erosivity index with 70.97 and 33.44 mm were also assigned to Darkesh and Abiary Bojnourd stations, respectively.

Assessment frequency of springs has become an important issue for land use planning, especially water resource identification and environmental protection.The purpose of this study is to produce a spring occurrence potential map in Bojnourd Basin, based on a logistic regression method using Geographic Information System (GIS) and remote sensing (RS). The locations of the springs (359 springs) were determined in the study area. In this study, 14 effective factors including spring were used in the analysis: lineament density, distance to lineament, distance to drainage, drainage density, normalized difference vegetation index (NDVI), profile curvature, tangential curvature, surface rate, vector dispersion, precipitation, elevation, geology, aspect and slope. Binary logistic regression coefficients of the variables by selecting 300 spring randomly. 59 another spring were used for validation that 80.6% of the springs were correctly predicted. The accuracy of the model was measured using ROC curves which showed that accuracy is 86.6 percent which indicates that the model shows high accuracy in the analysis of spring occurrence potential in the study area. The results showed that the distance of lineaments, distance of drainage, drainage density, vegetation index, profile curvature, tangential curvature, vector dispersion, precipitation and slope have the greatest impact on the occurrence of springs. Finally, spring occurrence potential map was divided into four probably classes of very low, low, medium and high. According to the survey results, this method can be used to identify sources of groundwater in karstic zones and has important role in better management of the karstic Basins.

Studying the forage quality of range species is among the important factors required for range management. In the present study, the forage quality of range species including Onobrychis transcaspica, Onobrychis radiate, Astragalus brevidens, Melica ciliate, Agropyron pectiniforme, and Sangisorba minor were investigated at three phenological stages. The study was conducted in the rangelands of Bojnourd. At each phenological stage, sampling was performed randomly with five replicates. Forage quality indices including CP, ADF, DMD, and ME were measured in the laboratory. The results showed that the forage quality of the study species was higher as compared with flowering and seeding stages, so that with the advancing age of the plant, crude protein, dry matter digestibility, and metabolizable energy reduced and ADF increased. In comparison with grasses, Legumes had the highest CP content (14.53% and the lowest ADF content (43.91%) in all three phenological stages. Among the study species, the maximum and minimum crude protein content was recorded for Astragalus brevidens and Agropyron pectiniforme, respectively.
Analysis of variance showed that the effects of species and phenological stages were significant (P

Dracocephalum kotschyi is one of the medicinal and aromatic plant that find in natural site of mountainous and high lands. This plant incase has a lot essence is attend. In traditional medicine، this plant use for fever reduction، joints pain، rheumatism، inflammation against and sore recovery. Present study was carried out to know of ecological characteristic of this species for introduce and dense cultivation of this plant on farm land and then use in medical industries. Such as this plant natural sites were controlled of destroying. This study was carried out in range land of Bojnourd in 2008. In the site، the studies were climatically characteristic، geology، stand type، codominant plant and vegetable variation، physical and chemical analyses of the soil. Results showed that Dracocephalum kotschyi could be adapted for regions with semiarid- cold climate، annual rainfall average of 320 mm and annual temperature average of 10. 22 c. Dracocephalum kotschyi have dispersed in northern and north- west slope and altitude 1600- 1800 m of sea level in rocky area. The soils physical and chemical analyses showed that the soil is very shallow with loomy texture، pH= 7. 57- 7. 6، Ec=. 555 ds/m، CEC= 11. 14- 11. 9 Cmol/kg. The stand type was Stachys inflata- Festuca ovina and the codominant plants were over 58 species. Average of canopy covers and density were 0. 122%، 361 shrubs in hectare respectively.

Measuring forage quality of dominant species is a prerequisite of proper management in rangelands. In this research, nutrient values of seven species were evaluated at three Phenological (vegetative growth, flowering and seed production) stages. In this study, a completely randomized design with five replications was used in Bojnord rangelands. Species included: Sanguisorba minor, Onobrychis transcaspica, Onobrychis radiata, Astragalus brevidens, Melica ciliate, Agropyron repens and Agropyron pectiniforme. The measured forage quality parameters included: crude protein (CP), acid detergent fiber (ADF), dry matter digestibility (DMD) and metabolizable energy (ME). According to results, forage qualities in all of the studied species were higher in vegetative growth than flowering and seed production stages. CP, ME and DMD of the studied species were decreased approaching to the end of growing season, while ADF values were increased. Legumes had higher percentage of crude protein (14.53%) and the lower percentage of ADF (43.91%) in all phenological stages, while perennial grasses had CP and ADF of 8.1% and 54.14% respectively. High and low CP percentages were obtained in Astragalus brevidnes and Agropyron pectiniforme, respectively. According to the results, significant differences were observed among the species and phenological stages for all measured and calculated forage quality factors (p<0.01).